We calculate below the carbon footprint of a hypothetical delivery of English pellets to a customer 27 miles from our depot in Okehampton. 27 miles is chosen somewhat arbitrarily as a reasonably typical distance from depot to customer. The English factory chosen for the sake of the example is the closest large-scale plant to Okehampton. Verdo's pellet plant in Andover can produce its heat using either biomass or gas, but does not produce its own green electricity. It is more efficient than smaller-scale local producers (although it must pull in its wood from a wider radius because of its scale). It therefore represents a reasonably optimistic scenario for supply of local pellets, where the savings in transport emissions are balanced to some extent by the emissions from the power stations that supply the electricity for production (and from the gas for drying when not drying with biomass).
Forever Fuels supplies Verdo's pellets in the south. The carbon footprint can be compared with that of more distant pellet plants (in the UK and outside) that are powered by biomass CHP (we offer Invergordon [by road and by sea] and Storuman as examples of British and Swedish plant respectively).
| Andover wood-pellet production plant |
 | | Wood pellet production takes a significant amount of heat and electricity. Pellet plants that use wood to produce Combined Heat & Power (CHP) for their process have the lowest carbon footprint, but this is an expensive solution only practical at large scale. Many small-to-medium pellet plants take the significantly cheaper option of using their lower-quality biomass to produce only heat for the process, and either import their electricity or produce it with a fossil-fired generator (e.g. oil or gas).
Because Andover can produce its heat with wood or gas, we demonstrate two scenarios below: one where the heat is produced with wood (i.e. zero carbon contribution) and the other where the heat is produced with gas. As can be seen, the absence of CHP takes the overall carbon footprint from even a plant that heats with wood to a level equivalent to remote CHP-powered pellet production with significantly more transport carbon emissions. If the plant also dries with fossil fuel, the carbon footprint is significantly higher than CHP-produced pellets that have travelled long distances.
The lower-quality biomass resource (i.e. the woody material not suitable to be put into the pellets) is often not sufficient to meet the whole heat-load. It may be supplemented by better-quality biomass to keep the carbon footprint down. But it is more economically-efficient to supplement it with fossil fuels. The reality of a plant with the capability to use both wood and fossil fuel for drying will probably be between the two scenarios, neither using all biomass nor all gas, but a combination of the two, giving a carbon footprint between the two. Producers will prefer to use their wood by-products as far as possible, for economic as well as environmental reasons. We would expect a good proportion of Verdo's heat to be produced with wood, giving a carbon footprint towards the lower end of the range. |
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| | kWh per tonne | x | kg of CO2 per kWh | = | kg of CO2 released per tonne of pellets produced |
| Electricity | 120 | x | 0.617 | = | 74.05 |
| Natural gas | 1000 | x | 0.2255 | = | 225.54 |
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| Andover to Okehampton |
 | | The emission factor is the amount of carbon dioxide emitted per mile by the vehicle for a return journey (fully laden on the outward leg and empty on the return), divided by the number of tonnes carried. The emission factor is then multiplied by the number of miles the vehicle travels. Generally, the larger the lorry, the lower the carbon footprint and cost per tonne of pellet-haulage. But it is not usually practical to deliver to customers in the largest lorries. To minimize cost and carbon emissions without sacrificing convenience to the customer, where deliveries are not close to the port or factory, FF transports pellets from port or factory to local depots in large, 28-tonne bulk tippers, and then from the depot to the customer in smaller delivery vehicles more suitable for the smaller stores and less-accessible roads that are often encountered. |
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| Miles | x | Emission factor per tonne | = | kg of CO2 released per tonne of pellets delivered to depot |
| 128 | x | 0.129 | = | 16.51 |
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| Okehampton to customer |
 | | FF has a fleet of delivery vehicles that can carry between 10 and 20 tonnes. DEFRA suggest that such vehicles would emit around 0.214 kg CO2/t mile. The actual figure would vary significantly, depending how many tonnes the vehicle was able to deliver in a single run. Where appropriate, FF aims to combine deliveries to maximize efficiency. Efficiency will thus improve as the market grows and consolidates, increasing opportunities to combine deliveries. |
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| Miles | x | Emission factor per tonne | = | kg of CO2 released per tonne of pellets delivered to customer |
| 27 | x | 0.303 | = | 8.18 |
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| Total carbon footprint at the customer's property |
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| | Total Miles | x | Combined emission factor per tonne | = | kg of CO2 released per tonne of pellets from factory to customer |
| Drying with wood | 155 | x | 0.637 | = | 98.74 |
| Drying with gas | 155 | x | 2.092 | = | 324.28 |
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| Energy source | kg of CO2 equiv. released per MWhth |
| Wood pellets (drying with wood) | 20.57 |
| Wood pellets (drying with gas) | 67.56 |
| Oil | 307.86 |
| LPG | 259.07 |
| Natural gas | 225.54 |
| Coal | 413.42 |
| Electricity | 617.07 |
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